New Study Predicts a Slight Cooling of North Atlantic Sea Surface Temperatures over the Next Decade

Pierre Gosselin at NoTrickZone provided an introduction to a recently published paper in his post IPCC Scientist Mojib Latif Sees North Atlantic Cooling Over Next Decade…Confirms Oceans Play Crucial Role. The paper is Klöwer et al. (2014) Atlantic meridional overturning circulation and the prediction of North Atlantic sea surface temperature. It is a study of the cause of the multidecadal variability of the North Atlantic sea surface temperatures (known as the Atlantic Multidecadal Oscillation).  They find that multidecadal variations in Atlantic Meridional Overturning Circulation, driven by the North Atlantic Oscillation, precede the changes in North Atlantic surface temperatures.  Their findings suggest the “present warm phase of the AMO is predicted to continue until the end of the next decade, but with a negative tendency”.

The abstract of Klöwer et al. (2014) reads:

The Atlantic Meridional Overturning Circulation (AMOC), a major current system in the Atlantic Ocean, is thought to be an important driver of climate variability, both regionally and globally and on a large range of time scales from decadal to centennial and even longer. Measurements to monitor the AMOC strength have only started in 2004, which is too short to investigate its link to long-term climate variability. Here the surface heat flux-driven part of the AMOC during 1900–2010 is reconstructed from the history of the North Atlantic Oscillation, the most energetic mode of internal atmospheric variability in the Atlantic sector. The decadal variations of the AMOC obtained in that way are shown to precede the observed decadal variations in basin-wide North Atlantic sea surface temperature (SST), known as the Atlantic Multidecadal Oscillation (AMO) which strongly impacts societally important quantities such as Atlantic hurricane activity and Sahel rainfall. The future evolution of the AMO is forecast using the AMOC reconstructed up to 2010. The present warm phase of the AMO is predicted to continue until the end of the next decade, but with a negative tendency.

In his blog post, Pierre Gosselin has translated portions of the press release for the paper, which clarifies what the authors mean with the last sentence of the abstract. Co-author Dr. Mojib Latif of GEOMAR Helmholtz Centre for Ocean Research Kiel says, according to Pierre:

Our model tells us that the phase with a rather high surface temperatures in the North Atlantic will continue also over the coming decade, however with a lightly negative trend.

And as Pierre also notes, a slight negative trend means cooling. It’s also important to note that Dr. Latif was discussing surface temperatures of the North Atlantic, not the Atlantic Multidecadal Oscillation Index, which is detrended North Atlantic sea surface temperature data.

To further clarify the impact of this on global sea surface temperatures, see Figures 1 and 2. Figure 1 compares the sea surface temperature anomalies from January 1975 to present for the North Atlantic and for the rest of the global oceans. The warming rate of the North Atlantic doubled that of the rest of the global oceans in that time, and that additional warming is a response to the warming phase (not warm phase) of the Atlantic Multidecadal Oscillation.  So it’s blatantly obvious that the North Atlantic contributed to the warming of global sea surface temperatures since the mid-1970s.

Figure 1

Figure 1

Sometime after the turn of the century the Atlantic Multidecadal Oscillation peaked.  Due to the volatility of the data and the short time frame, it’s tough to determine when it peaked. But for illustration purposes, Figure 2 compares the same two sea surface temperature data subsets starting in 2003.  The surface of the North Atlantic has cooled slightly over that time, while the surfaces of the rest of the global oceans show very little warming.

Figure 2

Figure 2

Proponents of the hypothesis of human-induced global warming like to claim that the additional warming of the North Atlantic was caused by manmade forcings. The CMIP5 climate models (the models used by the IPCC for their 5th Assessment Report) contradict that claim.  I illustrated this quite plainly about a year ago in the post Questions the Media Should Be Asking the IPCC – The Hiatus in Warming.  There I wrote:

[Start quote from earlier post.]

We can illustrate the Atlantic Multidecadal Oscillation using the method recommended by Trenberth and Shea (2006), and it was to subtract global sea surface temperature anomalies (60S-60N, excludes the polar oceans) from sea surface temperature anomalies of the North Atlantic (0-60N, 80W-0).  They used HADISST data and so have I.  In the time-series graph in Figure 3, I’ve also smoothed the AMO data with a 121-month running average filter.  As shown by the blue curve, the North Atlantic has a mode of natural variability that causes its sea surface temperatures to warm and cool at rates that are much greater than the variations in the surface temperatures of the global oceans.  And we can see that the variations occur over multidecadal time periods (thus the name Atlantic Multidecadal Oscillation).  Keep in mind that the Atlantic Multidecadal Oscillation is responsible for some (but not all) of the warming of land surface temperatures in the Northern Hemisphere during the more recent warming period, according to the climate scientists at RealClimate.  (See also Tung and Zhou (2012) Using data to attribute episodes of warming and cooling in instrumental records.)

Figure 3

Figure 3

If we subtract the modeled global sea surface temperatures from the modeled sea surface temperatures of the North Atlantic (shown as the red curve in Figure 3), we can see that the forced component of the CMIP5 models (represented by the multi-model ensemble mean) does not simulate the observed multidecadal variations in the North Atlantic.  That is, there is very little difference between the modeled variations in global and North Atlantic sea surface temperature anomalies.  The comparison also strongly suggests that the Atlantic Multidecadal Oscillation is NOT a response to manmade greenhouse gases (or aerosols) used by the climate modelers to force the warming (or cooling) of sea surface temperatures of the North Atlantic.

[End quote from earlier post.]

Back to Klöwer et al. (2014):

The abstract of Klöwer et al. (2014) notes the surface temperatures of the North Atlantic impact hurricanes and Sahel rainfall.  The North Atlantic sea surface temperatures also have strong influences on rainfall patterns in North America, on land surface temperatures throughout the Northern Hemisphere and on Arctic sea ice (because the Arctic Ocean is open to the North Atlantic).

ADDITIONAL INFORMATION

For those new to the topic of the Atlantic Multidecadal Oscillation (AMO) refer to the NOAA Frequently Asked Questions About the Atlantic Multidecadal Oscillation (AMO) webpage and the posts:

SOURCES

The HADSST3 data presented in Figures 1 and 2 and the HADISST data in Figure 3 are available through the KNMI Climate Explorer.  The North Atlantic surface area percentage is presented in the NOAA webpage Volumes of the World’s Oceans from ETOPO1.

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About Bob Tisdale

Research interest: the long-term aftereffects of El Niño and La Nina events on global sea surface temperature and ocean heat content. Author of the ebook Who Turned on the Heat? and regular contributor at WattsUpWithThat.
This entry was posted in Atlantic Multidecadal Oscillation, Model-Data Comparison SST. Bookmark the permalink.

5 Responses to New Study Predicts a Slight Cooling of North Atlantic Sea Surface Temperatures over the Next Decade

  1. Thanks, Bob.
    As always, you give us a great ocean view!

  2. mwhite says:

    Bob, how credible is the Unisis presentation

    http://weather.unisys.com/surface/sfc_daily.php?plot=ssa&inv=0&t=cur

    Seems overdone when compared to others

    http://weather.gc.ca/saisons/animateweb_e.html?imagetype=images_loop&imagename=……..00_054_G6_global_I_SEASON_tm@lg@sd_000.png&nbimages=1&clf=1&bc=sea

  3. Bob Tisdale says:

    mwhite, I will agree with you. The Unisys maps appear extreme…even with their color coding biased toward cooling. We’ll know in early November when October SST data are posted. Sure wish the NOAA NOMADS website was online so I could investigate the weekly data.

    Cheers.

  4. Arno Arrak says:

    Bob Tisdale – you make excellent temperature graphs and should be commended for that. Unfortunately I find most of them unhelpful because of various quirks that temperature data are laden down with. And Klöwer et al. (2014) paper on Atlantic meridional overturning circulation etc..that you report upon is not equal to the task they have undertaken. First of all since we are talking of the North Atlantic history the most important part is left out by their choice of cutoff date. Most of the temperature curves begin in 1975, just five years after the end of mid-century cooling, and completely leave out the big warming at the turn of the century. That tells me right away that the authors are completely ignorant of my 2011 paper that covers these events in depth. I run into this situation often when so-called “mainstream” climate scientists simply do not read scientific literature in their own field. Various other things are also an annoyance. Detrending, which you say is meant to eliminate the human-caused part of the warming is a total waste because there is nothing to eliminate. Another one is belief in volcanic cooling which which does not exist as I proved in my book. As far as warming is concerned, the Arctc that is continuous with the North Atlantic is the only part of the world today that us still warming. That is thanks to the warm currents carrying Gulf Stream water north. It all started at the turn of the century that is crucially interesting fir North Atlantic but completely left out of this paper. That alone is reason to regard their work as worthless. But there is more. It can be demonstrated that the so-called “greenhouse” warming that Hansen constantly was pushing does not even exist. Undoubtedly you know that there is no greenhouse warming now and there has been none for the last 18 years. This applies to the North Atlantic too but they see fit to simply ignore it. Problem is that during this entire time of pause or hiatus of warming atmospheric carbon dioxide as measured by the Keeling curve steadily increased. The Arrhenius greenhouse theory used by IPCC has been predicting warming because of this fact and getting nothing for all these 18 years. If you are a scientist and your theory predicts warming for 18 years and you get nothing at all you know that the theory is invalid and belongs in the waste basket of history. Fact is we do have a theory that correctly describes our climate, the Miskolczi greenhouse theory or MGT. It has been known since 2007 and was vilified on the web and blacklisted as soon as they found out what its predictions were. Where Arrhenius predicts warming MGT predicts what actually happens: addition of carbon dioxide to the atmosphere does not warm the air. No papers reporting this could be published and post-docs were kept ignorant of its existence. MGT differs from the Arrhenius theory used by the IPCC in being able to handle a situation where more than one GHG simultaneously absorb in the infrared. Arrhenius can handle only one – carbon dioxide – and is incomplete. The most important GHGs in the earth atmosphere are water vapor and carbon dioxide. According to MGT they co-operate in forming an optimal joint absorption window in the IR. The optical thickness of this window is 1.87, determined by Miskolczi from first principles. If you now add carbon dioxide to the atmosphere it will start to absorb in the IR just as the Arrhenius theory says. But this will increase the optical thickness. And as soon as it happens water vapor will start to diminish, rain out, and the original optical thickness is restored. The carbon dioxide that was added to air will of course keep absorbing but the parallel reduction of water vapor I referred to will keep the total absorption constant and no warming is possible. This is why there is no warming today despite a constant increase of atmospheric carbon dioxide. This is of major importance to climate science. First, it clearly makes the existence of enhanced greenhouse effect impossible. Since that is said to cause anthropogenic global warming it follows that AGW itself does not exist either. It is nothing more than a pseudo-scientific fantasy, invented by an over-eager climate worker to justify the greenhouse hypothesis.And the same goes for runaway warming, Hansen’s boogey-man. He warned us that if we keep burning fossil fuels we will suffer the fate of Venus which means runaway global warming. Hansen was wrong both about us and about Venus. Even the very high carbon dioxide concentrations in geologic history did not lead to any runaway warming. By leaving out essential facts I enumerated this paper does not tell us anything important about the North Atlantic Ocean. If I had been the reviewer I would not have approved it in this form.

  5. Pingback: Climate Pacemaker: The AMOC | Science Matters

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